Torque wrench adapter for power tools



May 1, 1956 E. REDMON TORQUE WRENCH ADAPTER FOR POWER TOOLS Filed Dec.21, 1954 INVENTOR Ernest Z. 18612772022 BY M ATTORNEY TORQUE WRENCHADAPTER non POWER TOOLS Ernest L. Redmon, Columbus, Ohio ApplicationDecember 21, 1954, Serial No. 476,805

3 Claims. (Cl. til-52.4)

This invention relates generally to torque wrenches, and moreparticularly to an improved torque wrench adapter for use in detachablycoupling socket-type wrench heads of various sizes to an associatedhand-held power tool, such as an electric motor driven hand drill.

In the past, numerous types and constructions of torque wrenches havebeen proposed for use in imparting tightening rotation to nuts orsimilar fastening devices, particularly in operations where it isdesirable that such nuts be tightened upon an associated bolt or studonly through the application of a predetermined torque force. However,previous torque wrenches of this type of which I am aware are generallycharacterized by a relatively high degree of mechanical and structuralcomplexity and consequent high cost.

It follows, therefore, that the primary object of my invention is toimprove generally upon previous torque wrenches by providing arelatively structurally simple, yet mechanically efiicient torque wrenchadapter for hand-held power drills which is operable in combination withsuch drillsto receive various sizes of socket wrench heads and impartrotational torque forces thereto of variable and adjustable magnitude,whereby to insure the tightening of an associated nut positioned in thesocket wrench head to a given tension upon an associated bolt or stud.

Another object of this invention is to provide a torque wrench adapterfor power driven hand drills which is relatively compact in constructionand comprised of but few and relatively simple mechanical parts, andwhich may be easily connected with an ordinary power driven hand drillto detachably receive varying sizes of socket wrench heads and easilyadjusted to impart various predetermined torque forces thereto.

A still further object of the invention is to provide a torque wrenchadapter of this type which is composed in the main of external, readilyadjustable, and unmachined parts of rugged construction, and which maybe manufactured at comparatively low costs, andwhich, at the same time,possesses the necessary mechanical efiiciency to enable the same toeffectively accomplish its intended purpose.

' For a further and more complete understanding of the present inventionand the various additional objects and advantages thereof, reference ismade to the following description and accompanying drawing, wherein:

Fig. 1 is a longitudinal vertical sectional view, partially inelevation, showing my improved torque wrench adapter in operativerelation to an associated driving tool and socket wrench head;

Fig. 2 is a transverse vertical sectional view taken along the line 22of Fig. 1; and

Fig. 3 is a perspective view of the adapter.

Referring now to the drawing, my improved torque wrench adaptercomprises a driving shaft, generally indicated at 5, which is formed atone end with a straight bit-like extension 6 adapted to be clampedwithin and drivingly received by the chuck portion 7 of an ordinaryelectric motor driven rotary hand drill or tool, indicated generallyat8, after the manner of a standard drill bit. The shaft 5 is furtherformed with a screw-threaded intermediate portion 9, and terminates atits opposite end in an integral, relatively diametrically enlarged,disk-shaped head 10. Preferably, the bit-like extension 6 of the shaft 5is smooth and unthreaded as shown in the drawing, but if desired, theshaft may be threaded throughout its length, with the exception of thehead, without adversely affecting the operation of the adapter, as willbe hereinafter more fully explained.

Enclosing the disk-shaped head 10 of the shaft 5 is a generallycylindrical clutch drum, indicated in its entirety by the referencenumeral 11. The drum 11 is composed of a hollow, open end, cup-shapedsection 12 and an annular end wall 13 which is welded, or otherwisesuitably and permanently secured, as at 14, to the section 12 after thehead 10 is positioned therein. The end wall 13 of the drum is formedwith a central bearing opening 15 through which the shaft 5 extends, andwhich defines on the end Wall an inner, flat, annular surface 16arranged for frictional engagement with the complemental flat annularsurface 18 formed on the inner side of the head 10 of the shaft 5.

The cup-shaped section 12 of the drum includes an integral, relativelyreduced, axially extending driven shaft 19 which terminates at the outerend thereof in a square, multiangular, wrench head-receiving extension20. Advantageously, the extension 20 may be suitably recessed to receiveand retain a spring-pressed hall 21 which extends partially outwardlyfrom one of the sides of the extension 20 to frictionally engage one ofthe wall surfaces defining a square, multiangular chamber 22 formed in asocket wrench head 23. The wrench head 23, as shown in Fig. 1,constitutes a standard socket-type wrench head formed with amultiangular nut-receiving socket 24 in the forward end thereof. It willbe understood that wrench heads 23 having varying sizes of nut-receivingsockets may be used interchangeably with the present torque wrenchadapter in accordance with the size of nuts desired to be tightenedduring work operations.

Rotatably carried on the shaft 5, adjacent the end wall 13 of the clutchdrum, is an annular bearing washer 25, The washer 25 is abutted on oneside thereof by an end of a relatively heavy coil compression spring 26disposed in encircling relation to the intermediate screwthreaded region9 of the shaft 5. The opposite end of the spring 26 is abutted and heldby an adjustable stop nut 27 which is threaded onto the intermediateregion 9 of the shaft 5. A lock nut 28 is also threaded on the region 9of the shaft 5 and, when tightened down against the stop nut 27, servesto hold the latter against accidental backing-off movement on the shaft.

As will be understood, the spring 26.is normally maintained undercompression between the stop nut 27 and the bearing washer 25, and undersuch condition causes the inner wall surface 18 of the head 10 of theshaft 5 to be drawn into tight frictional engagement with thecomplemental inner surface 16 of the end wall 13 of the drum 11, wherebyto effect a yieldable frictional driving engagement between the shaft 5and the drum l1 and a wrench head 23 disposed on the extension 20. Thetension upon the spring 26, and consequently the force tending to holdthe head 10 in engagement with the drum 11, may be adjusted withinrelatively wide limits by simply adjusting the position of the stop nut27 axially on the intermediate threaded region 9 of the shaft. Forexample, in nuttightening operations where it is desired to impartrelatively high torque forces to the work, the stop nut 27 is tighteneddown on the shaft 5 toward the head 10 thereof to compress the spring 26to a maximum. Cons 3 versely, where; relatively light torque isrequired, the nut 27 may be backed off on the shaft 5 to a point wherethe spring is only lightly compressed, thereby decreasing the forcestending to hold the head in tight frictional engagement with. the endwall 1 of theqdrum.

In operation, the bit-like shank 6 of the adapter is tightly clamped inthe chuck of the hand. drill 8 in order that the adapter may be rotatedat high speeds upon energization of. the motor of the drill or tool 8.The stop nut 27 is then adjusted on the screw-threaded. region. of theshaft 5 to a position to impart the desired tensionupon the head 10 ofthe shaft in. accordance withthe torqueforce desired tov be imparted toanassociated nut to bev tightened The position of the stop-nutv 27 ;uponthe shaft 5 for any desired torque outputmay: be easily predetermined byfirst testingtheadapter with a suitable tudihal adjustment on theintermediate region of said shaft; spring means carried on said shaftbetween said stop means and the end wall of said clutch drum for boldingthe annular inner surface of said disk head in frictional,non-slipping,torque transmitting engagement with the annular innersurface of the end wall of said clutch drum, said head slipping andturning relative to said drum when predetermined torque forcesareapplied to the interengaging surfaces thereof; and a second shaftcarried torque-measuring; gauge, and, if desired, theintermediatescrew-threaded region of. the shaft 5 may be suitably indexed'orgraduatedsoas to provide ready visual reference forthe setting; of thestop. nut, 27 in, adjusting the torqueoutput. of the adapter. Aftersetting of the stop nut 27-, a suitable size wrench head 23 is selectedin accordance withthe size of nut to be tightened, and the Wrench headsnapped, onto the extension of the adapter. The wrench head is thenplaced over the nut to be tightened and the motor of; the hand drill 8is cnergized=, whereupon the component parts of the adapter and the nutto be tightened are rotated in unison until the resistance to furthertightening of. the nut reaches or exceeds the predetermined torqueoutput of the adapter, at which time the drum 11, shaft 19, andwrenchheadZZtare stopped from rotating and the head 10 of the shaftslips and rotates within the drum 11.

It will thus be see'n that the present invention provides a mechanicallyefficient, structurally simple, and inexpensive torque wrench adapterfor power tools which is characterized by its rugged construction, easeof assembly and adiustability, and ready accessibility to parts foradjustment, repair, or replacementpurposes. 7

While I have shown and described. indetail a single preferred embodimentof myiinventiomit will beunder stood that the same is susceptible tocertain modifications as to details of construction and design withoutdeparting, from the spirit of the invention or the scope of thefollowing claims. a V

I claim: g

1 A torque wrench adapter comprisinga shaft formed at one end forinsertion within the chuck of a rotary handtool and having anintermediate, externally screwthreaded' region thereon, said shaft atthe opposite end thereof being provided with a' diametrically enlargeddisk head having a flat,annular, inncr surface; a hollow. clutchdrumvofnon-adjustable, unitary construction rotatable on and enclosingthe disk head of said shaft and having an end wall formed with anopening through which said shaft extends, said end wall having a flat,annular, inner surface arranged for frictional engagement with theannular inner surface of the disk head of said shaft; stopmeansthreadedly carried in an open position for'longibyand extending axiallyoutwardly fronmsaitl cl'utuzhrhumv at the end thereof opposite the saidend wall and formed at the outer end thereof with amultiangularextension to drivingly receive a socket-type wrench head.

2. A torque wrench adapter as defined in tuna i and.

wherein said stop means comprisesr apair of internally threaded nutsadjustable on the intermediate threaded region of said first-named shaftto vary the tension of said spring means'and thereby the force holdingthe annular inner surface of. said. disk head inv frictional engagementwiththe inner surface ofthecnd wall of clutch drum.

3.. A torque wrench adapter comprising a first. shaft formed at one endwith a bit extension fordriying connection with a rotary power tool,said shaft; furtherincluding an intermediate, externally screwfthreadedregionand a. diametrically enlargcdheadat theend thereof opposite to thebit extension, the head, of first shaft beingv formed. with a fiat,annular, inner surface;

a generally. cylindrical drum of nonradjustable, unitary construction.rotatably carried on and'enclosing the head of said first shaft, said:drum havinga fiat, annular, end

wall arranged for frictional, power-transmittingengage-.

ment with the flat, anuulan, inner surface of, said head; a second shaftformed integrally with said drum extending axially and longitudinallyoutward from the end thereof opposite said flat, annular, end wall,said. second shaft terminating in a multiangular extension for the.detachable reception of a, driven wrench head; openly. disposed,longitudinally adjustablq stop. means threadedly .disposed around, theintermediate portion of said. first shaft; and coiled, compression.type,springmeans carried; on: said. first. shaft, said. spring meansvbearing, at one end against said stop means. and, at its opposite, end.against the end wall of said: drum, whereby to. urge the. flat, annular,inner surface of said head normallyv ms power-transmitting, frictional.engagement. with the an nular end wall of said drum, the adjustmentofsaid stopv means on, said first shaft serving to vary the compression.

of said spring means and. the frictional forcesfdeveloped. thereby inholding; theinterrengaged wall surfaces. 'of.

the head and drum in power-transmitting engagement,

whereby to enable said head to turn relative to said drum whenpredetermined forces restraining the drum against rotationv areencountered.

References Cited in the'file of this patent UNI ED STATES PATENTS23-35574 Thompson et al. Nov. 30, 1943' 2 ,471, 14 Gilman May 31-, 1949

